Expression of osteopontin and its receptors in ameloblastomas.

This study used an immunohistochemical method to examine the expression of osteopontin (OPN) in 30 ameloblastomas and of integrin alpha(v) and CD44v6 in 20 of these 30 ameloblastomas. We found that the positive staining rate in ameloblastomas was 87% for OPN, 45% for integrin alpha(v), and 90% for CD44v6. Both ameloblast-like and stellate reticulum-like cells showed a high expression of OPN and CD44v6. There was also a strong integrin alpha(v) immunostaining on the cell membrane of osteoclasts. Binding of OPN to osteoclast cell membrane receptor integrin alpha(v) can activate the osteoclast and increase its osteolytic activity. In addition, binding of OPN to ameloblastoma tumor cell membrane receptor CD44v6 can enhance tumor cell migration, invasion and spread. Therefore, we suggest that the local aggressive behavior and high osteolytic ability of ameloblastomas in the jawbones can be explained by the high expression of OPN and CD44v6 in ameloblastoma cells and the high expression of integrin alpha(v) in osteoclasts.